How do you adjust a GM TBI?
Unplug the IAC valve located on the passenger side, rear of the throttle body. Start the engine. Insert a T-30 size Torx driver into the Idle adjustment screw that is located behind the plug removed earlier. Turn the screw to adjust the idle speed to 650 RPM +/- 50 RPM.
How do you reset TBI?
6- Start engine and run for 5 seconds, turn engine OFF and wait at least 30 seconds. This will reset the IAC control.
Can you adjust the idle on a throttle body?
The curb idle on the fuel injected engines should be checked periodically but not adjusted unless off specifications by more than 50 rpm. The idle speed adjusting screw is located on the side of the throttle body. You can find the the throttle body by following the accelerator cable to its end.
How do you adjust TBI TPS?
Loosen the throttle position sensor retaining screw with a Phillips-head screwdriver. Adjust the TPS by moving it back and forth until the voltage is between 4.0 and 5.5 volts. Hold the TPS in place and tighten the retaining screw with the Phillips-head screwdriver.
How do you test TBI IAC?
The easiest way to check to see if it is extending and retracting is to pull it out the IAC and hold the pintle (the cone shaped thing) with your thumb. Have someone power up the ECM it should extend then retract while keeping some pressure on the pintle (it will unscrew itself if you don’t do this).
Why is TBI running rich?
IF you are running rich: Either your injectors are stuck open (usually an ECM fault), the fuel pressure is too high, or the ECM is getting incorrect signals from one of the sensors. If one of the sensors is bad, it is either the TPS, the O2 sensor or the MAP sensor. These sensors are what controls the fuel mixture.
How do you test IAC on a TBI?
How do I adjust the idle RPM?
Set idle speed adjusting screw, clockwise to increase rpm, counter-clockwise to decrease rpm. Idle rpm range should be 950 to 1050 rpms. Adjust idle mixture by turning idle mixture screw slowly clockwise until the engine runs poorly. Note position.
How do I reduce the idle RPM?
Turn the idle screw, now exposed from the protective rubber coating, in order to adjust the idle. Loosen the screw in a counter-clockwise fashion to increase idle speed or tighten it in a clockwise manner in order to decrease the idle speed. Ideally, you will want the idle to rest at 650 RPM.
How do you adjust the fuel pressure on a 350 TBI?
To increase the fuel pressure, turn the adjustment screw counter-clockwise. This will cause the spring to exert more pressure on the regulator diaphragm and regulate at a higher pressure. Monitor your adjustment with a fuel pressure gauge. A little adjustment should be all that’s necessary, 1-2 PSIG at a time.
